Background: Among congenital nasal deformities, proboscis lateralis is one of the rarest. Boo-Chai classified proboscis lateralis into four groups. Recently, we encountered a new case of proboscis lateralis with median cleft lip. We noticed that this classification had not been considered according to convalescence and embryologics, and further refinement seemed to be needed. Methods: We reviewed all cases of proboscis lateralis reported in English through 2009 and classified them by intercanthal distance. Results: A total of 34 studies involving 50 cases were reviewed. Six cases were identified as having normal intercanthal distance. Three of them presented nose abnormalities and fit Boo-Chai group II category. The other three were consistent with group I. Hypertelorism was observed in 27 cases and was further divided into two groups based on the occurrence of a frontal encephalocele. Seventeen cases without a frontal encephalocele were compatible with Boo-Chai groups III and IV. The other 10 cases associated with a visible encephalocele had encephalopathy; most died at an early age, and long-term survival cases suffered developmental delay and mental retardation. Seventeen cases were defined as hypotelorism, and all cases also presented as holoprosencephaly. Conclusions: The redefined classification contains two new groups: group V as hypertelorism with encephalocele and group VI as hypotelorism. A new classification scheme is proposed as not only convenient for clinical application but also embryologically accurate.
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